Coronary Bifurcation Lesions: To Stent One Branch or Both?
- Volume 16 - Issue 9 - September, 2004
- Posted on: 8/1/08
- 0 Comments
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True bifurcation lesions, representing up to 16% of coronary targets for intervention, have been associated with higher peri-procedural complication rates and lower long-term patency rates.1–6 In the contemporary interventional era, several approaches have been proposed to treat bifurcation lesions.7,8 Coronary stents improve the immediate angiographic results by reducing lesion recoil and achieving better scaffolding, but stents are associated with increased thrombotic complications and later restenosis in bifurcation lesions.8–11 With different stenting approaches, there are 2 principal techniques frequently used: 1) stenting the main branch with balloon angioplasty of the sidebranch; or 2) stenting of both bifurcation branches. Conflicting results have been reported for these two technical approaches.8–13 Thus, we sought to analyze our own experiences among 50 consecutive patients with “true bifurcation” lesions treated using either stenting of the main branch and balloon angioplasty of the sidebranch versus stenting of both branches.
Study population. Between March 2001 and November 2002, a total of 50 patients underwent percutaneous coronary revascularization at our center for management of symptomatic true bifurcation lesions (type 1 or 2 according to Lefévre’s classification).12 Only lesions in which there was a > 50% diameter stenosis in both the parent vessel and the ostium of the contiguous sidebranch with reference diameter > 2.0 mm were considered for treatment and/or analysis.
Quantitative analysis of the coronary segments was performed by an independent reader blinded to the early and late results, using a validated angiographic archiving method (Medcon™ Telemedicine Technologies, Tel-Aviv, Israel), with the dye-filled catheter as a reference. The diameter of the normal segment proximal to the traced area in the parent vessel was used to determine the parent reference diameter. The sidebranch reference diameter was determined from the diameter of the traced area in the normal segment distal to the lesion in the branch. The minimal luminal diameter (MLD), reference diameter and percent stenosis were calculated as the mean values from two projections. Lesion length was defined as the distance from the proximal to the distal shoulder of the lesion.
Coronary intervention. After placement of the guiding catheter (6 or 7 French), two wires were inserted in the distal bed of the two branches. Balloon angioplasty was conducted by sequential inflation of a semi-compliant balloon in each branch or by a simultaneous inflation of both branches. Stenting was performed using two methods. The first technique was stenting the main vessel and balloon inflation of the sidebranch. As a general rule, if the sidebranch diameter was > 2.5mm, a stent was also deployed in the sidebranch. Otherwise, stenting the sidebranch was subsequently conducted only in cases of imminent sidebranch closure or residual stenosis of the sidebranch > 50%. Eight patients (16%) were treated using two stents according to the initial interventional plan (sidebranch vessel diameter > 2.5 mm). In the remaining 42 patients, a single stent was initially planned, but 24 of these cases (57%) crossed over into the double stent group due to unsatisfactory angiographic results. Simultaneous kissing balloon inflation was frequently performed on completion of the procedure.
All patients received aspirin as well as heparin bolus infusion to achieve an activated clotting time between 250–300 seconds (> 300 seconds if not treated using glycoprotein IIb/IIIa antagonists). Patients received either oral clopidogrel (loading dose 300 mg and 75 mg once daily for 1 month). Antiplatelet medications (e.g., glycoprotein IIb/IIIa inhibitors) were given at the discretion of the operator. All patients were followed closely at our outpatient clinic and all clinical events were adjudicated and recorded using source documentation (hospitalization chart and coronary angiography) by our research team.
Study endpoints and definitions. Procedural success was defined as an angiographic residual stenosis < 30% in the main vessel and the sidebranch. Sidebranch compromise was defined as abrupt closure or decrease in coronary flow in the sidebranch at any time during the procedure. Acute vessel closure and/or stent thrombosis was defined as the occurrence of vessel closure or stent thrombosis determined angiographically. Target lesion revascularization (TLR) was defined as any repeat percutaneous intervention to the target lesion (parent or sidebranch) or any coronary bypass grafting needed on the target vessel during follow-up. Six-month total major adverse cardiac events (MACE) were defined as death, myocardial infarction (MI) or TLR during the follow-up period plus in-hospital MACE. Post-procedural MI was defined as occurrence of typical ischemic chest pain of greater than 30 minutes with cardiac enzyme (CK-MB) elevation of > 3 times the upper limit of normal. Post-procedural cardiac enzymes were obtained for suspected myocardial ischemia, manifested by recurrent post-procedure chest pain, hemodynamic instability or new electrocardiographic changes of ischemia.
Statistical analysis. Chi-square tests or Fischer exact tests were used for analysis of categorical variables when appropriate, and the student’s t-test was used for analysis of continuous variables. Multivariate logistic regression analysis was performed to determine significance of variables related to in-hospital and long-term MACE (included in the model factors with p-value < 0.1 by univariate analysis). Statistical analysis was performed using STATISTICA software, and a p < 0.05 was considered significant for all analyses.
Patient characteristics. Of the 50 patients in our cohort, thirty-two (64%) were treated using two stents, and 18 patients (36%) were treated using stenting of the main branch and balloon angioplasty of the sidebranch. The treatment groups were generally similar with respect to age, gender, risk factors and lesion location (Table 1). Pre-procedure angiographic characteristics were also similar between the two groups except for higher values of percent diameter stenosis in the sidebranch vessel in the group treated using two stents (Table 2).
Procedural characteristics are shown in Table 2. Kissing balloon was used more often in the double stenting group (72% versus 39%; p = 0.02). The maximum inflation pressures were significantly lower in the single stent group for the sidebranch vessel (9.4 ± 3.3 versus 11.7 ± 2.8 atm; p = 0.03). As expected, the number of stents used per patient was significantly higher in the double stent group. The fluoroscopy time was significantly higher in the double stent group (28 ± 17 minutes versus 18±7 minutes; p = 0.01) and the amount of contrast material used also tended to be higher in this group. The use of antiplatelet medication was similar between groups.
Angiographic procedural success was 87.5% in the single stent group and 100% in the double stent group (p = 0.10; Table 3). This difference was due to failure to achieve < 30% residual stenosis in the sidebranch of two patients (12.5%) in the single stent group.The MLD of the parent vessel increased from 0.20 ± 0.36 mm to 3.06 ± 0.5 mm after stenting in the single stent group and from 0.31 ± 0.39 mm to 2.98 ± 0.33 mm in the double stent group. These results were not significantly different in the two groups. The MLD of the sidebranch vessel increased from 1.1 ± 1.1 mm to 2.02 ± 0.66 mm after angioplasty in the single stent group and from 0.6 ± 0.6 mm to 2.41 ± 0.58 mm in the double stent group. The acute lumen gains achieved in the double stent group were higher as compared with the single stent group. The post-procedure percent diameter stenosis of the sidebranch vessel was significantly higher in the single stent group (18 ± 25% versus 4 ± 8%; p = 0.005).
There were no early deaths or need for emergent coronary artery bypass grafting in either group (Table 4). In the double stent group, two patients sustained subacute stent thrombosis resulting in acute myocardial infarction (occurring at 2 days and 5 days following the index procedure). The stent thrombosis involved the sidebranch (diagonal artery) in the first case and both the left anterior descending and diagonal arteries in the second. In both patients, the procedures were not completed using kissing balloon inflation. Two additional patients in this group had post-procedure MI as compared to 1 patient in the single stent group who sustained peri-procedural MI due to complete occlusion of the sidebranch.
All patients were followed for 6 months and 35 (70%) were asymptomatic (Table 4). The incidence of clinically driven repeat TLR was 37.6% in the double stent group as compared to 5.6% for the single stent group (p = 0.01). Angiographic restenosis was documented in 40.6% of the double stent group as compared to 11% of the single stent group (p = 0.05). The majority (69%) of the restenosis in the double stent group involved the sidebranch only, with the rest involving both the main and the sidebranch. By multivariate analysis adjusted for baseline differences, stenting the sidebranch was a borderline predictor for 6-month MACE (odds ratio = 10.3; 95% confidence interval, 0.9–116; p = 0.053), while the use of kissing balloon was not an independent predictor for reduced restenosis.